The present invention generally relates to a mounting structure of a switching unit, and more specifically, to a structure for detachably mounting the switching unit in a switching unit-holding aperture by an elastic force of a holding pawl attached at the side of a case for the unit.
Conventionally, there have been known a various types of switching units, such as an elastic holding-pawl whose one end is fixed at the side of a case of a switching unit and presses the inner surface of a peripheral wall for forming a switch unit-holding aperture of a switch unit-mounting member such as a panel by an elastic force thereof, and the pawl has an engaging portion protruding in a direction away from the side of the case, so that the engaging portion is brought into engagement with an engaging opening formed at the inner face of the wall of the holding aperture to detachably hold the unit into the holding aperture of the panel.
According to the mounting structure, when the unit is removed from the holding aperture, the engaging portion thereof is completely removed from of the engaging opening against the elastic force of the pawl before the unit is pulled in a direction in which the unit is removed from of the holding aperture, and thus the unit can be disengaged from the holding aperture.
When the engaging portion is completely removed from the engaging opening against the elastic force of the pawl in the case where the engaging opening does not penetrate through the wall of the holding aperture, a screwdriver must be inserted into a very small gap between the surface of the pawl and the inner surface of the wall of the holding aperture in order to make the pawl bend in a direction in which the pawl is separated from the inner surface of the wall.
In such an operation, there have been problems whereby the contact between the screwdriver and the side of the case or the wall of the holding hole may cause the damage to the side of the case or the wall. Furthermore, in the case where plural pawls are attached at the side of the case, when the unit is removed from the holding aperture, such a very difficult operation is required wherein each engaging portion of the plural pawls is removed from each of the engaging openings by the screwdriver at the same time.
On the other hand, in the case where the engaging opening penetrates through the peripheral wall of the holding aperture, an appropriate jig is required to inserted into the engaging opening from the outside of the wall to enable the engaging portion, to be removed from the engaging opening in order to disengage the unit from the holding aperture. In this case, there has been a problem that a tool, i.e. the jig, is also required to carry out the operation. Furthermore, in the case where the plural pawls are attached at the side of the case, when the unit is removed from the holding aperture each engaging portion of each pawl is required to press out from each of the engaging opening at the same time. The operation is also very difficult to carry out. For resolving the problems, there has been proposed a special tool which is specially designed to press both the engaging portions from the outside of the wall of the holding aperture at the same time. However, there have been problems whereby a special tool corresponding to each kind of unit is required and such requirement is very uneconomical. The different pitch with respect to the arrangement of the engaging portions and the engaging depth of the engagement between the engaging portion and the engaging opening prevent the same, kind of the tool from adapting thereto, resulting in the requirement of a different tool corresponding to every unit.